Where You Are & Where You Were
Intellectual development is greatly influenced by inter individual variation related
to genetic uniqueness, changes in family & career responsibilities, cohort, educational level, income, marital status and physical & mental health.
Individual profiles of intellectual change can be separated out from group trends, allowing growth, decline and stable functioning to be examined on a case-by-case basis. These reveal that the reasons for intellectual growth or decline are complex and multifaceted, based on the unique experiences of adult life.
Some individuals seem to decline in all mental abilities during middle adulthood, while others are just as capable at age 70 as they were when they were younger.
Changes in teaching strategies and years of schooling are 2 possible explanations of why more recently born cohorts outperform earlier cohorts in tests of verbal meaning and inductive reasoning.
Human Growth & Development
Robert C. Gates